Monitor Issue (goes dim randomly)

We have about 175 computers here at work, all of which I am responsible for fixing. I've had a problem with one in particular for a few weeks and I heard that this problem has existed before I started working which was about 2 months ago.

Problem: Monitor "randomly" goes partially or completely dim.

The only thing I've found that fixes the problem is unplugging the power cable from the monitor and computer for about one minute then plugging them back up. Sometimes this works, sometimes it doesn't.

my computer has the same problem somewhat (screen stays dims and becomes bright occasionally) I tried changing my monitor's output level from 0.7v to 1.0v and back with no permament change, changing this level will temporarily fix it, but after a few minutes it dims (or brightens) again .. I'm no electrician, but I think it may be faulty wiring